Clinical significance and association of GSTP1 hypermethylation with hepatocellular carcinoma: A meta-analysis

Objective: To quantitatively investigate the effect of GSTP1 hypermethylation on hepatocellular carcinoma (HCC) using a meta-analysis of available case-control studies. Materials and Methods: Previous studies have primarily evaluated the incidence of GSTP1 hypermethylation in HCC and corresponding control groups, and compared the incidence of GSTP1 hypermethylation in tumor tissues, pericancer liver tissues, normal liver issues, and nontumor liver tissues with that in other diseases. Data regarding publication information, study characteristics, and incidence of GSTP1 hypermethylation in both groups were collected from these studies and summarized. Eleven studies, including 546 cases of HCC and 575 nontumor cases, were identified for meta-analysis. Results: Statistically significant odds ratios (ORs) of GSTP1 hypermethylation were obtained from tumor tissues and nontumorous liver tissues of HCC patients (OR 2.63, 95% confidence interval [CI]: 1.77-3.89%, P < 0.0001), tumor tissues of HCC patients, healthy liver tissues of patients with other diseases (OR 7.29, 95% CI: 2.87-18.51%, P < 0.0001), tumor tissues of HCC patients, and liver tissues of patients with nontumorous liver diseases (OR 2.13, 95% CI: 1.10-4.13%, P < 0.05). The pooled analysis showed significantly increased ORs of GSTP1 hypermethylation (OR 2.21, 95% CI: 1.01-4.84%, P < 0.05) from HCC tissues and cirrhotic tissues. Conclusions: The results of this meta-analysis suggest that GSTP1 hypermethylation induces the inactivation of GSTP1 gene, plays an important role in hepatocarcinogenesis, and is associated with an increased risk of HCC.